Research ArticleBIOPHYSICS

Dynamic spectrin/ankyrin-G microdomains promote lateral membrane assembly by opposing endocytosis

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Science Advances  11 Sep 2015:
Vol. 1, no. 8, e1500301
DOI: 10.1126/sciadv.1500301


Current physical models for plasma membranes emphasize dynamic 10- to 300-nm compartments at thermodynamic equilibrium but subject to thermal fluctuations. However, epithelial lateral membranes contain micrometer-sized domains defined by an underlying membrane skeleton composed of spectrin and its partner ankyrin-G. We demonstrate that these spectrin/ankyrin-G domains exhibit local microtubule-dependent movement on a time scale of minutes and encounter most of the lateral membranes within an hour. Spectrin/ankyrin-G domains exclude clathrin and clathrin-dependent cargo, and inhibit both receptor-mediated and bulk endocytosis. Moreover, inhibition of endocytosis fully restores lateral membrane height in spectrin- or ankyrin-G–depleted cells. These findings support a non-equilibrium cellular-scale model for epithelial lateral membranes, where spectrin/ankyrin-G domains actively patrol the plasma membrane, analogous to “window washers,” and promote columnar morphology by blocking membrane uptake.

  • ankyrin-G
  • spectrin
  • palmitoylation
  • epithelial lateral membrane
  • clathrin
  • endocytosis
  • plasma membrane
  • microdomain

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